Re: [linux-dvb] [PATCH] Userspace tuner

Alex Deucher
2007-09-14T18:52:23Z

On 9/14/07, Markus Rechberger <mrechberger@gmail.com> wrote:
> On 9/14/07, Manu Abraham <abraham.manu@gmail.com> wrote:
> > Joerg Roedel wrote:
> > > On Fri, Sep 14, 2007 at 11:57:59AM +0400, Manu Abraham wrote:
> > >>>>> What do you think about IOMMU?
> > >>>>>
> > >>>>>
> > >>>> Just because AMD or INTEL want to invent some whizzy new technology it
> > >>>> doesn't say anything about the TV card development and retail business.
> > >>>> Intel and AMD have teams of Linux engineers helping operating system
> > >>>> developers bring their ideas and technologies to new platforms. That's
> > a
> > >>>> million miles away from any of the TV board vendors I know of, who have
> > >>>> little or NO fulltime linux developers and consider the < 5% market
> > >>>> fringe at best.
> > >>>>
> > >>> it helps to virtualize devices and introduces newer features for that.
> > >>> Some interesting projects could be derrived out of that, there are
> > >>> quite a few interesting papers floating around how drivers could be
> > >>> handled in future.
> > >>>
> > >> IOMMU can be considered similar to the AGP GART, which is similar,
> > >> remapping the Addresses, as far as i understand.
> > >
> > > Common new IOMMUs have only very few in common with the AGP GART. In
> > > fact, with current modern IOMMU hardware it will be possible to
> > > implement secure userspace device drivers that are even able to do DMA.
> > > This is not possible with the GART.
> > >
> > >> Though you get a physical to virtual translation, what about interrupts,
> > >
> > > Modern IOMMUs are able to remap interrupts. This will solve the problem
> > > with PCI interrupt sharing.
> >
> > What CPU's are we talking about ?
> >
>
> upcoming x86-64 processors from the AMD side. I'm not into what Intel
> is doing in that area at the moment.

All AMD64 chips have an IOMMU. Only Intel's most recent chips do.

Alex